The un-tone-mapped display is based on the display transform from the OCIOv2 demo config which uses the built-in transform. It’s an inv EOTF for an sRGB Display with D65 whitepoint.

```
<BuiltinTransform> {style: "UTILITY - ACES-AP0_to_CIE-XYZ-D65_BFD"}
```

I made a version of it for OCIOv1 using Jed Smith’s inverse EOTF Nuke script to create a LUT for OCIO. Here’s the Nuke script (copy-paste into Nuke)

```
set cut_paste_input [stack 0]
version 13.1 v1.013601b
push $cut_paste_input
Group {
name InverseEOTF
label "\[value eotf]"
selected true
xpos -192
ypos 50
addUserKnob {20 EOTF_tab l EOTF}
addUserKnob {4 eotf t "Choose the inverse EOTF to apply for the target display device." M {None "sRGB Display" BT.1886 "Gamma 2.6" PQ HLG "" "" "" ""}}
eotf "sRGB Display"
}
Input {
inputs 0
name Input
xpos 400
ypos -160
}
Dot {
name Dot1
xpos 434
ypos -96
}
set N9838a800 [stack 0]
Dot {
name Dot3
xpos 544
ypos -96
}
set N9838a400 [stack 0]
Dot {
name Dot4
xpos 654
ypos -96
}
Multiply {
channels rgb
value 10
name Multiply1
label "scale input 0.1x for 1000 nit match between PQ and HLG"
xpos 620
ypos -76
}
Expression {
temp_name0 Yd
temp_expr0 0.2627*r+0.6780*g+0.0593*b
expr0 r*pow(Yd,(1-_g)/_g)
expr1 g*pow(Yd,(1-_g)/_g)
expr2 b*pow(Yd,(1-_g)/_g)
name HLG_InverseOOTF
xpos 620
ypos -28
addUserKnob {20 CONSTANTS_tab l CONSTANTS}
addUserKnob {7 _g t "Gamma: Extended model for gamma variation according to peak display luminance and surround luminance: BT.2390-8 p32" R 0 2}
_g {{1.2*pow(1.111,log(Lw/1000)/log(2))*pow(0.98,log(max(1e-6,Lamb)/5)/log(2))}}
addUserKnob {7 Lw R 600 4000}
Lw 1000
addUserKnob {7 Lamb t "ambient luminance level in nits" R 0 200}
Lamb 5
}
Expression {
expr0 r<=1/12?sqrt(3*r):_a*log(12*r-_b)+_c
expr1 g<=1/12?sqrt(3*g):_a*log(12*g-_b)+_c
expr2 b<=1/12?sqrt(3*b):_a*log(12*b-_b)+_c
name HLG_OETF
selected true
xpos 620
ypos 5
addUserKnob {20 CONSTANTS_tab l CONSTANTS}
addUserKnob {7 _a t alpha}
_a 0.17883277
addUserKnob {7 _b t beta}
_b {{1-4*_a}}
addUserKnob {7 _c}
_c {{0.5-_a*log(4*_a)}}
}
push $N9838a400
Expression {
expr0 pow((c_1+c_2*pow(r*Lw/10000,m_1))/(1+c_3*pow(r*Lw/10000,m_1)),m_2)
expr1 pow((c_1+c_2*pow(g*Lw/10000,m_1))/(1+c_3*pow(g*Lw/10000,m_1)),m_2)
expr2 pow((c_1+c_2*pow(b*Lw/10000,m_1))/(1+c_3*pow(b*Lw/10000,m_1)),m_2)
name ST2084_InverseEOTF
xpos 510
ypos -43
addUserKnob {20 CONSTANTS_tab l CONSTANTS}
addUserKnob {7 m_1}
m_1 {{2610/4096*(1/4)}}
addUserKnob {7 m_2}
m_2 {{2523/4096*128}}
addUserKnob {7 c_1}
c_1 {{107/128}}
addUserKnob {7 c_2}
c_2 {{2413/128}}
addUserKnob {7 c_3}
c_3 {{2392/128}}
addUserKnob {7 Lw t "Display peak luminance in nits" R 600 4000}
Lw 10000
}
push $N9838a800
Expression {
expr0 sign(r)*pow(fabs(r),1/p)
expr1 sign(g)*pow(fabs(g),1/p)
expr2 sign(b)*pow(fabs(b),1/p)
name power
xpos 400
ypos -70
addUserKnob {20 Params_tab l Params}
addUserKnob {7 p l power R 0.2 2}
p {{eotf?2+eotf*0.2:1}}
}
Switch {
inputs 3
which {{max(0,eotf-3)}}
name SwitchInverseEOTF
xpos 400
ypos 5
}
Output {
name Output
xpos 400
ypos 80
}
end_group
```

It’s intent is for diagnostic purposes. In this case getting the ACES display to match Nuke’s default display-referred sRGB view transform without any tone mapping for comparative purposes.